Tonga Country Report - SPREP

The transects were located perpendicular to the shoreline through the mangrove
ecosystem at all of the major mangrove areas on the Fanga'uta lagoon (Figure 1). The
surveys indicate that zonation is simple and marked, with different species assemblages
forming zones parallel to the shoreline from the lagoon fringe to the edge of dry land. The
lowest zone (to seaward) consists of Rhizophora mangle and/ or R. stylosa. Landwards of
the Rhizophora zone is,a Bruguiera gymnorrhiza zone, with occasional Lumnitzera
littorea. The Bruguiera zone becomes interdispersed with Excoecaria agallocha towards
land. These distribution patterns 'follow the zonation described by Ellison (1998) at
Folaha/ Nukulietulu, Fatai and Sopu.
The transect data show that there is overall high human impact on the mangroves of the
Fanga 'Uta lagoon. Locations with higher level of human impact, requiring rehabilitation,
were shown to be Havelutotu, East Ha'ateiho, Ha'ateiho, East Halaleva Neitongo,
Alakifonua and South Popua. Most common impacts are cutting of trees, dumping of
garbage, reclamation for construction of houses. House construction usually introduces
problems of sewage disposal. These problems are not new; they have been documented
for over 10 years.